Your Name: ___________________________________ Role:______________

Lab Partners: ________________Role:_____ ________________Role:_____

Problem: How can substances in a liquid mixture be separated?

Hypothesis: _______________________________________________________

_________________________________________________________________

_________________________________________________________________

Materials:                 15 cm ruler             large paper clip
    250 mL beaker          solvent                 scissors
    food colorings         filter paper            apron

Caution:

Procedure:

1. Cut your filter paper into 4 strips that are each 10 cm long and 2
cm wide. Make sure that the bottom end of each piece has been cut square. Poke a small hole into each strip 8 cm from one end.
2. Using a pencil, label one strip BLUE, one GREEN and one BLACK at the
top by the hole.
3. Place a tiny spot of the appropriate food coloring on the strips 1
cm from the end opposite the label.
4. Pour about 50 ml of solvent into the 250 mL beaker.
5. Put the straightened paper clip through the hole of one piece of
filter paper and carefully lower it into the beaker until it is
just touching the solvent, but not so low as to have the food
coloring in the solvent.
6. When the solvent has almost risen to the paper clip take the strip
out of the beaker. Immediately measure how far the top of each
color zone has traveled. Measure from the 1 cm line to the top
of each zone. Record in your data table.
7. Repeat steps 5 and 6 for the other strips and then try one
additional color from a pen or marker.
8. When dry, staple one strip of paper to your lab sheet.
9. Using the formula:

R_f = distance traveled by the color / distance traveled by solvent

calculate the R_f for each distinct color on the strip.

Observations:

Data:

Diagram:

Conclusion: _______________________________________________________

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Questions:

1. Did a physical or chemical change take place when separating the liquid mixture? Explain.
2. What color usually made it to the top of the strip?
3. How can you tell if a dye is made of only one color?
4. Are the food colorings elements, compounds or mixtures?
5. Why is it important to make lines on the paper in pencil?
6. A color component of a dye has a R_f of 0.25. Where would this color
be found on the paper strip?
7. Using the table below, identify the commercial food dyes that were
used in this lab?